How to heal/fill this type of damage to a mesh?
For a flat mesh:
You can repair most issues like this by holding Alt and then right-clicking on the boundary edge. Now the perimiter of the hole will be selected. Now press Ctrl+F > Grid Fill. If it is a space with only four vertices/edges, you can simply press F to create the new face.



For a curved mesh: This is a little more complex, but still can be done. You will need to set the cursor position to the center of the curve/sphere. Now set the Pivot Point to 3D Cursor. You now are able to duplicate vertices on each loop and rotate them to the correct positions in the mesh. Simply select each quad of vertices and press F. This is more tedious, but is still effective.